Valentia ObservatoryOzone Monitoring
Valentia Observatory has been conducting Ozone measurements since 1993 and is
currently one of an international network of sites involved in the monitoring
of ground level, total column and stratospheric ozone.

Upper Air Monitoring Activities
The vertical distribution of ozone in the atmosphere is measured by
balloon-borne ozonesondes, which are launched during winter and spring
months. Additional ozonesonde
launches are made as part of European-wide monitoring and field research programmes.
As part of the GAW (Global Atmospheric Watch) Global Ozone Observing System
the Observatory has played a very active role in EU funded research
projects including,
SESAME (the Second European Stratospheric and Mid latitude Ozone Experiment),
TOASTE (the Tropospheric Ozone and Stratospheric-Tropospheric Exchange), FASTEX
(the Fronts and Atlantic Storm Tracking Experiment) and THESOE (the Third European
Stratospheric Ozone Experiment). More recently Valentia has been actively involved
in the MATCH campaign which is part of the OSDOC (Ozone Soundings as a tool
for Detecting Ozone Change) experiment.

Vertical Ozone Profile derived from Ozonesonde ascent

Ground-based Monitoring Activities
Ground-based monitoring of total column ozone and UV-B radiation levels are continuously
conducted at Valentia Observatory, using a Brewer spectrometer (right). These
data contribute to the daily analysis of Northern Hemisphere total column ozone
as produced by WMO Daily Ozone Mapping Centre (Thessaloniki, Greece) and the
WOUDC (the World Ozone and UV Data Centre, Toronto, Canada).

Ground-level ozone is measured on a continuous basis using an API Model
400 Continuous UV Absorption Ozone Analyser. This monitoring is done
as part of the national
ground level ozone monitoring programme conducted by the EPA (Environmental Protection
Agency).

Ozone
Ozone is a gas, blue in colour and with a strong odour, which is formed by the
action of ultra-violet light on oxygen. While ozone is present from the surface
of the earth up to the stratosphere its concentrations are significant at two
parts of the earth's atmosphere, at ground level and in the stratosphere at a
height of between 17,000 and 23,000 meters where high concentrations occur. This
high concentration is referred to as the ozone layer. The maintenance of this
thin layer is essential for the health of humans, animals and plant life because
it absorbs harmful ultra-violet radiation from the sun.

Seasonal dependence of Total Column Ozone at Valentia Observatory.

Based on Spring 1993 to Spring 2000 final values.On the other hand,
high levels
of ozone at the ground are harmful. "Good up high, bad nearby" is a
phrase that is often used to describe the value of ozone. At ground level ozone
is a pollutant. Here it is formed during warm conditions and strong sunlight
by reactions among nitrogen oxides, and volatile organic compounds from car exhausts
and industry. Consequently, high concentrations of ground level ozone are often
found in cities during the summer, where they contribute to smog and can cause
chest pain, throat irritation and coughing.
Most of the world's ozone is formed near the equator, spreads out and is transported
north and south by large-scale global circulations. The ozone layer is denser
at high latitudes than it is over the tropics. The concentration of ozone at
any location is prone to variations due to many factors, among them being seasonal
changes and changes in prevailing air masses.

Ozone is destroyed naturally through the interaction of other gases
in the stratosphere, and is replenished in the same cycle. This natural
cycle is being interrupted
by human activity such as the release of other gasses among them being Chloroflourocarbons
(CFC's) and emissions of nitric oxide from aircraft.